The Dometic 40,000 BTU Large Furnace is a compact, lightweight heater boasting a quiet operation thanks to reduced air turbulence. For easy and flexible installation, it may be placed vertically or horizontally. With the most duct configurations on the market, you can distribute heat exactly as you need it. Access door and thermostat sold separately. Please ensure the existing cutout will accommodate this model: 9 in. H x 16-1/2 in. W x 20 in D.